Subglottic and tracheal stenosis can lead to high morbidity and mortality of individuals, due to limited airflow. Two forms of stenosis exist, congenital, caused by abnormal development of the trachea, and acquired, usually due to iatrogenic causes. The study of subglottic and tracheal stenosis has been limited to gross morphologic descriptions of inadequate airways. Surgical correction remains challenging, often with poor results. The principal investigator has a strong interest in the prevention and treatment of pediatric airway abnormalities. The proposed projects represent a rare opportunity to investigate both forms of tracheal stenosis using immunohistochemical and gene identification techniques. Support for this project will allow the principal investigator to develop the needed basic science expertise to make significant improvements to existing techniques to prevent and treat tracheal stenosis. The murine model will be used to test the hypothesis that regional tissue controls the growth and morphology of underlying tracheal cartilage. Individual study elements include 1) identification of growth influences of individual tissue layers that surround the tracheal cartilage 2) conditioned media experiments to test the influence of soluble proteins derived from epithelium and perichondrium on tracheal cartilage growth 3) identification of the proteins that control growth. Long-term goals of the principal investigator involve establishment of an independent research laboratory that can investigate hyaline cartilage growth and respiratory mucosal inflammation, and identify genes and their protein products that control tracheal morphology.